An apparent descriptive method for judging the synchronization of rotation of binary stars

Abstract

The problem of the synchronous rotation of binary stars is judged by using a synchronous parameterQ introduced in an apparent descriptive method. The synchronous parameterQ is defined as the ratio of the rotational period to the orbital period. The author suggests several apparent phenomenal descriptive methods for judging the synchronization of rotation of binary stars. The first method is applicable when the orbital inclination is well-known. The synchronous parameter is defined by using the orbital inclinationi and the observable rotational velocity (V_1,2 sini)_M. The method is mainly suitable for eclipsing binary stars. Several others are suggested for the cases when the orbital inclinationi is unknown. The synchronous parameters are defined by usinga _1,2 sini,m _1,2, sin³ i, the mass functionf(m) and semi-amplitudes of the velocity curve,K _1,2 given in catalogue of parameters of spectroscopic binary systems and (V_1,2 sini)_M. These methods are suitable for spectroscopic binary stars including those that show eclipses and visual binary stars concurrently. The synchronous parameters for fifty-five components in thirty binary systems are calculated by using several methods. The numerical results are listed in Tables 1 and 2. The statistical results are listed in Table 3. In addition, several apparent descriptive methods are discussed.